A cable usable for incorporation in medical apparatus.
It is old to provide a cable by winding one or more strands of wire about a linear central wire in contact with the wire throughout at least a major part of the axial length of the central wire. However, with such prior art cables, the useful life is shortened due to fracturing of the central wire, particularly when it is of such relatively small diameters. Furthermore, such cables cannot be bent about such a relatively tight radii and still, satisfactorily transfer torque from one end to the other with high resolution due to the solid core wire taking a set. Additionally, it is hard to clean out all of the foreign material entrapped during the manufacture of the solid lumen helical cables.
Oldbergh U.S. Pat. No. 3,267,697 discloses a universal joint for automobiles that includes a plurality of multifilar spring units in a telescoped relationship. The inside diameter of the intermediate spring unit is slightly less than the outside diameter of the inner spring unit. During assembly, the inner unit is preloaded to cause radial contraction and after being inserted into the intermediate unit, it is allowed to expand. The radial intermediate coil is wound in the opposite direction from that of the winding of the inner and outer coils. Ruegg U.S. Pat. No. 25,543 and Hotchkiss U.S. Pat. No. 1,228,439 each disclose a flexible coupling member and a flexible shaft, respectively, each of which includes an intermediate coil wound in a direction opposite that of the radially inner and outer coils. Sperling U.S. Pat. No. 1,279,773 also discloses a flexible shaft having oppositely wound coils.
Lerwick U.S. Pat. No. 3,811,446 discloses an endarterectomy apparatus that includes an electric motor which drives a pair of springs that in turn drive the input shaft of a converter. The inner coil is multifilar and is enclosed by an outer helical spring. Wampler U.S. Pat. No. 4,625,712 discloses an intravascular blood pump drivenly connected by a flexible shaft to a support unit that is located outside of the human body.
Kline U.S. Pat. No. 3,749,086 discloses a guide wire having an outer spring coil that extends between the proximal and distal tips, and in two embodiments, an inner coil only in the distal end portion of the outer coil and in two embodiments, a wire core extends between the tips.
Each of Takahashi U.S. Pat. No. 4,178,810 and Sanagi U.S. Pat. No. 4,632,110 discloses a coil spring having forceps mounted on one end thereof, and a manipulating handle mounted on the other end. Auld U.S. Pat. No. 4,646,736 discloses transluminal thrombectomy apparatus having a shaft comprised of a 3 mil gold wire helically wound about a 4 mil stainless steel arbor for rotating a tip and being driven by a prime mover. Mac Lean U.S. Pat. No. 2,955,592 discloses a medical instrument having a sheath that includes an outer coil and an inner coil. Willson discloses a vascular tissue removing device that includes a single layer multistrand closely spaced helically wound coil of wire (U.S. Pat. No. 3,749,085).
Kensey et al U.S. Pat. No. 4,664,112 discloses a catheter bendable about a radius of curvature, e.g. 3", and having a working head rotated at a high speed by a drive assembly. In one embodiment, the drive assembly includes two interlaced helical wires having their distal ends joined to a cutting tip. The two wires are wound about a guide wire to rotate about a guide wire, having outside diameters of 0.01", and are loosely wound.
Kline U.S. Pat. No. 3,757,768 discloses a spring guide catheter wherein a plastic tube is heat shrunk over a coil spring, while O'Neil U.S. Pat. No. 4,145,247 discloses a pacer lead wherein a coil conductor is enclosed in an insulating layer.
Each of Samson et al U.S. Pat. No. 4,538,622 and Leary U.S. Pat. No. 4,545,390 discloses a PCTA guide wire that includes a main wire having a proximal cylindrical portion, a tapered intermediate portion, a cylindrical distal end portion of a smaller diameter than the proximal cylindrical portion, a helically wound coil having a proximal portion joined to the tapered portion, and a distal tip joined to one or both of the main wire distal end and the coil. In Samson, the coil includes two coil portions of different materials.
One of the problems encountered in the prior art is the lack of a very small diameter, highly flexible cable that has a relatively long life even when bent about relatively small radii for forming a part of the medical apparatus; for example, rotating or otherwise moving all or part of a medical device or medical subassembly and is medically clean. In order to overcome problems such as the above, as well as others, this invention has been made.